Summary:
The Cytochrome P450 enzyme CYP1B1 [1] only occurs in cancer cells [2][3]. When certain phytoalexins such as resveratrol and salvestrol are ingested these phytoalexins are converted by the P450 enzyme into piceatannol [4], which is fatal to cancer cells but not human cells [5][6].

[1] http://en.wikipedia.org/wiki/CYP1B1
[2] http://cancerres.aacrjournals.org/content/57/14/3026.short
[3] http://secure.salvestrol.ca/secure/doc/isomtalk_schaefer2010.pdf
[4] http://en.wikipedia.org/wiki/Piceatannol
[5] http://www.nature.com/bjc/journal/v86/n5/abs/6600197a.html
[6] http://www.orthomolecular.org/library/jom/2007/pdf/2007-v22n01-p039.pdf

In 2003 it was noticed that cancer cells contain enzymes no other cells do.

There is a family of enzymes called the Cytochrome enzymes and a subclass of those are the P450 enzymes and the individual variants of those are man.

A researcher for a pharmaceutical company named Gerry potter began working with the Cyp17 variant that shows up in prostate cancer.

There is a fairly recent technique called a "pro-drug" paradigm where instead of a drug killing a cell a drug combines with an existing chemical. He designed a molecule that reacts with the Cyp17 enzyme forming a chemical that kills only that cell and does not harm normal cells. It worked in a petri dish, it worked in mind and it worked in monkeys. At that point it was sold for $2B.

It went to clinical trials in 2012 and worked so well they stopped the test because the placebo group wen't getting better and this was considered unethical.

http://www.sfgate.com/cgi-bin/article.cgi?f=%2Fc%2Fa%2F2012%2F06%2F02%2FMNI11ORI84.DTL

Here are the 174,000 papers on P450 Cytochrome enzymes and cancer:

https://scholar.google.ca/scholar?hl=en&q=p450+cytochrome+enzyme+cancer&btnG=&as_sdt=1%2C5&as_sdtp=

After this made Potter a wealthy man he kept going. He learned another variant of the P450 family appears in all cancer cells:

http://cancerres.aacrjournals.org/content/57/14/3026.short

Note this is the proper peer reviewed cancer journal not some hippy shit. Big pharma funded research.

So be began to design a pro-drug that would work on CYP1B1 the same way Abiraterone Acetate works on CYP17 for prostate.

But, he found it already existed in nature and in the greatest concentration in tangerine peel; it's also present in high concentrations in strawberries, prune plums and asparagus.

The BBC picked up in the tangerine angle:

http://news.bbc.co.uk/2/hi/health/6987200.stm

Potter got an award:

http://www.salvestrol.ca/doc/Gerry%20Potter%20Honoured.pdf

So he extracted and tested it and it worked. Then he repeated the test after making another batch and it didn't work. He then figured out he's used organic tangerines the first time and sprayed fruit the second time.

It turns out the plant makes this chemical in response to mold. If there's no mold the plant had no reason to make the chemical in any great amount and it's production is reduced by up to 90%.

This explains why cancer went from being something very few doctors had even heard of in 1900 to the second leading cause of death today. That is there is both cause and correlation spraying antifungals is the reason cancer has skyrocketed.

Incidentally antifungals are wahat is also killing the bees, not neonicotinoid pesticides - Monsanto Is quite right in saying no lab has ever confined they hurt bees:

http://qz.com/107970/scientists-discover-whats-killing-the-bees-and-its-worse-than-you-thought/

It's also what's killing all amphibians worldwide.

Potter reported his findings in Nature:

http://www.nature.com/bjc/journal/v86/n5/abs/6600197a.html

Now here's the problem. In medicine patents are only given out for drgs that are invented. Chemicals that already exist that cure disease cannot be patented which is sensible. That's why nobody can get a patent for the fact oranges cure scurvy.

The bad news is without patent protection nobody us willing to put up the $100M to FDA certify the CYP1B1 variant the way they were to put up that money for the CYP17 variant Abiraterone Acetate.

The good news is you can buy it over the counter. You might think of salvestrol's relationship to cancer in the same as vitamin C is to scurvy. Normally we get enough from citrus to allow the immune system to kill of cells that have divided improperly (which happens all the time, usually without event)

But just as industrial processing of food destroyed he vitamin C in warmed milk for babies resulting in an outbreak of infancy scurvy in 1911, our use of antifungals has taken away our bodies natural ability to fight cancer.

http://pediatrics.aappublications.org/content/108/4/e76.full

How do I know all this? I ran into this guy in a Starbucks in Toronto and it turned out he as from the same village in Wales I'm from and we became good friends and I took a series of lectures from him.

He died a few years ago of cancer - which sounds bad, but he died at 75, two years past the average age of death. Not bad for a guy that was told in 1990 he had six months to live because of a particularly aggressive for of non-Hodgkins lymphoma. He told nobody this and we were all surprised when he died. You could not tell he was sick, his quality of life was that good. He had a nice Jaguar too.

https://en.wikipedia.org/wiki/Brian_Sparkes

Here are the case studies:

http://www.natuurdietisten.nl/files/Salvestrolen%20case%20studies4.pdf
http://www.beating-cancer-gently.com/support-files/salvestrolcasestudies2.pdf
http://www.salvestrolen.nl/images/pagepictures/PDF/Salvestrol_3rd_case_studies_Schaefer_JOMSept2012.pdf

Here is a list of MD's and other health practitioners that use this stuff to treat cancer.

http://www.salvestrol.ca/ResellerPractitioner.asp

You don't need to be an MD to use this any more than you need to be an MD to give somebody vitamin C to cure scurvy.

There are downsides: 1) It takes about 6 weeks to work. If you only have a week to live it may not help. Although it does produce results very quickly so this may not strictly be true. A lot depends on diet as cancer cells use glucose directly while human cells use glucose to make adenosine triphosphate ("ATP"). This cancer patients need to avoid sugars like the plague cancer cells out-compete us for them.

2) The reaction of the pro-drug into picotanneol is controlled by an allele on gene P53 - you'll find references in the literature that "gene P53 is inactivated in most cancer patients" and this is why and how. But, 1/5 of people lack this allele and this stuff does nothing for them. I'm so sorry.

3) While it kills cancer cells it does not kill the souce of them and you have to take it forever. That's kind of a drag but it beats dying. Hopefully they will soon crack the code there and find a way to kill the mutant cell that is generating all these cancerous cells.

Disclaimer: I have no relationship in any form with any of these people or products and no conflicts of interest. And here is a paper by Brian Schaefer pointing out if you look for CYP1B1 you can use this to screen for cancer:

http://secure.salvestrol.ca/secure/doc/isomtalk_schaefer2010.pdf

Gerry Potter, Brian Schaefer and Dan Burke are the most prominent figures in this field, here's Burke giving a talk on the salvestrols. Burks is professor emeritus of pharmaceutical metabolism from London university:

https://www.youtube.com/watch?v=J4tpPlqMJ7Y

Disclaimer: I have no relationship in any form with any of these people or products and no conflicts of interest.